Suddenly one day my brain became foggy and my vision was clouded and since then short term memory has decreased, what could cause this?

Need seen: Could have been a stroke, but could have also been a migraine or a seizure. You need an MRI and good neuro exam.

Stroke or TIA : Brain fog is a description of the results of stroke and the loss of the ability to remember things involves the outer cortex of the brain. Seek evaluation from a neurologist to identify the cause of the initial stroke before you have another.